Electrical resistor



J1me 26;1962 w. w CLOUD 3,041,566

ELEQTRICAL RESISTOR Filed March 4, 1959 United States Patent 3,041,566 ELECTRICAL RESISTOR William'Wolcott Cloud, 65-64 S. Normandie Ave., Los Angeles 44, Calif. Filed Mar. 4, 1959, Ser. No. 797,295 Claims priority, application France Mar. 6, 1958 2 Claims. (Cl. 33832) The present invention includes a method of regulating an electric current in a circuit, whereby, by means of a controlling magnetic field, variation is made to take place in cohesion of separate magnetic and conducting elements carried in an insulating vehicle.

The invention also includes the apparatus enabling such a method to be performed, said apparatus comprising an enclosure containing said insulating vehicle and the magnetic and conducting elements, said enclosure being provided with electrodes and being associated to means for producing a variable magnetic field acting upon said elements.

In a specific embodiment of such an apparatus, the magnetic and conducting elements are constituted by particles of powdered magnetic and conducting material, mixed with or suspended in an insulating liquid such as oil.

In another embodiment, these elements are constituted by blocks of conducting material such as carbon, containing Within their mass a magnetic material such as iron dust in the case of reconstituted blocks, or iron masses in the case of composite blocks.

In the case of conducting and magnetic dust, the electrodes are themselves made of magnetic material.

In the case of the blocks, the electrodes are constituted by the end blocks of a pile of blocks, these end blocks being connected to the electric circuit by means of flexible leads.

The controlling field may be that of a solenoid crossed by a control current, it being of advantage to cause this field to act through the Walls of the enclosure, the latter being non-magnetic.

The controlling field could be that produced by permanent magnets suitably orientated to obtain the required variation of said field in the vicinity of said elements.

Lastly, the invention includes the regulating or amplifying installations making use of such apparatus, and particularly those in which it is necessary to regulate the voltage and the current of a shunt-type electric generator, notably of the type used on motor vehicles for the purpose of charging accumulators.

The description which follows, in conjunction with the accompanying drawing given by Way of example only and not in any limiting sense, will give a clear understanding of the manner the invention may be performed.

FIG. 1 is a highly schematic view of one embodiment of a regulator or amplifier according to the invention.

FIG. 2 is a highly schematic view of a variant of the embodiment.

FIG. 3 is an example of a wiring layout for the use of such a regulator.

The regulator illustrated in FIG. 1 includes an enclosure 1 the tubular wall 2 of which is made of nonmagnetic material. The open ends of the wall 2 have inserted into them insulating plugs 3 and 4 through which pass electrodes 5 and 6 made of magnetic material. The internal volume of enclosure 1 is filled with oil, this insulating liquid being mixed with powdered magnetic material such as iron dust, it being possible for the fineness of the powder to vary and to be such that it may remain in suspended form.

The wall 2 is surrounded by the turns of a regulator coil 7 through which can be made to flow a controlling electric current.

This current may be tapped from the terminals of a battery 8 by way of a rheostat 9 and a measuring instrument 10. Current from battery 8 is led, on the one hand, to electrode 6 and, on the other, through a utilization element 11 and a measuring instrument 12.

By varying the current in the solenoid 7, the field which results produces a varying degree of coagulation of the magnetic grains suspended in the oil, both between themselves and on contact with the magnetic electrodes 5 and 6, thus offering, to passage of the electric current in the utilization element 11, a degree of conductibility which is proportional tosaid field and hence to said control current.

It is another possibility to use a powder obtained by grinding composite blocks formed under pressure and heat from a homogeneous mixture of fine steel and carbon particles, for improving the mutual contact properties.

As shown in FIG. 2, the powder grains may be replaced by blocks 13 made of some conducting material such as carbon, which are in the form of discs or washers and which are arranged in a pile inside the tubular element 2a. These blocks may contain, in the dispersed state, magnetic particles or even magnetic discs of washers, buried or not in the blocks. The end blocks 14 and 15 of the pile are connected to electrodes 5a and 6a, which pass through the insulating plugs 3a and 4a, by means of flexible leads 16 and 17, which may be constituted by elements in the form of springs. The enclosure 2a is likewise surrounded by the windings of a control solenoid 7a.

Such a piece of apparatus can be used as a regulator and also as an amplifier, it being possible for the current passing through the variable-conductivity conducting assembly formed by the powder grains or carbon discs to be a sizeable multiple of the control current which generates the field in the solenoid.

Variation of the conductibility is very large; it is virtually nil in the absence of current in the solenoid 7 or in the solenoid 7a, but can reach large magnitudes the maximum of which is obtained when the field developed by the solenoid saturates the magnetic elements, the latter being conducting ones in the case of the mixture or of the suspended state, or merely magnetic in the case of the pile in FIG. 2.

As shown in FIG. 3, the regulating enclosure 18, constituted as illustrated in FIGS. 1 or 2, may be placed in series with the inductor windings 19 of a shunt-type electric generator the armature 20 of which is connected via leads 21 and 22 to the terminals of a buffer battery 23 which is itself capable of feeding utilization circuits schematically exemplified by a resistor 24. The control solenoid placed on the enclosure 18 comprises several coils, to wit: a voltage regulating coil 25 connected between leads 21 and 22 with interposal in series of a plurality of selenium rectifiers 26, or silicon rectifiers using the zener eifect; a current-regulating coil 27 connected in parallel to the terminals of a shunt 28 placed in series on the line 21, the coil 27 being fed via a selenium diode 29; a polarization coil 30 connected between line 21 and 22 the direction of the windings of which is such that its field may add or subtract itself, as the case may be, to or from the fields of the voltage and current coils, the latter being preferably wound in the same direction.

Naturally, a line-breaker is placed on line 21 ahead of the corresponding terminal of the battery 25, it being possible for this line-breaker to be replaced by a selenium valve 31 to avoid feedback of current into the generator. Such a layout comprises only purely static elements of inexpensive construction and devoid of all the drawbacks inherent to known regulators of the vibrating-contact type, for example.

The manner of functioning of such an installation is self-evident and requires no further description.

It is to be clearly understood that many modifications can be made to the manners of performing the invention described hereinabove without departing from the scope of the latter. Thus, for instance, the controlling field may be generated by one or more suitably orientable permanent magnets, by fixed permanent magnets associated to moving magnetic shunts, or else by coils which instead of surrounding the regulating enclosure would merely be placed in the vicinity of said enclosure.

What I claim is:

1. A variable electrical resistance device comprising a circuit of variable conductivity constituted of a plurality of separate non-permanently cohering and non-permanently magnetic bodies which are both electrically conductive and magnetically susceptive, each of which bodies is of fixed electrical resistivity, the said bodies composed of a homogeneous mixture of electrically conductive new magnetic particles and of magnetic particles bonded together in a fixed relative position in an aggregate structure characterized by the separation of a majority of the magnetic particles from like magnetic particles by at least one electrically conductive non-magnetic particle, a nonmagnetic and non-conductive liquid surrounding and immersing the said conductive circuit, a non-magnetic insulated enclosure containing the said circuit and liquid, means for applying a variable magnetic flux acting on the said conductive circuit through the walls of the said container, and means for electrical ingress to and egress from the said conductive circuit.

2. A variable electrical resistance device as described in claim 1 wherein the separate non-permanently cohering and non-permanently magnetic bodies are in the form of grains of powder.

References Cited in the tile of this patent UNITED STATES PATENTS 2,018,348 Dijksterhuis Oct. 22, 1935 2,500,953 Libman Mar. 21, 1950 2,586,544 Kesselring Feb. 19, 1952 2,620,466 Hagen Dec. 2, 1952 2,868,932 Schonhoif Jan. 13, 1 959 

